Oil gels are often desirable application vehicles for personal care products and cosmetic make-ups because they can provide a thin, water resistant, substantive film on skin. They are usually stable over time and convenient to apply. Some oily compounds exist in paste form at room temperature, such as Vaseline and lanolin, and may be directly utilized as an application vehicle. Others exist in liquid form, such as jojoba oil and bois oil, and may need to be converted to a gel form for use in a formulation. Various organic waxes, organic resins, and polymers have been employed as potential gelling agents for an oil medium. The resulting oil gels are generally very oily and particularly sticky if a polymer is utilized as the gelling agent.
Silicone polymers, particularly volatile silicones and low molecular weight silicones having a viscosity of below 50 cPs, have been used in an attempt to reduce the sticky feel and improve the extendibility but, they cannot reduce the oily feel and appearance on skin. Such an oily cosmetic composition is disclosed in U.S. Pat. No. 5,266.321, issued to Shukuzaki et al. Shukuzaki et al., disclose an oily make-up composition comprising an oil base, a silicone gel composition, and a cosmetic powder material. The silicone gel composition renders the make-up formulation less sticky and less oily, and provides a fresh, smooth feeling to the skin. The silicone gel composition disclosed therein consists essentially of a partially cross-linked organo polysiloxane and a low viscosity silicone oil. The silicone gel composition disclosed by Shakuzaki et al., however, is not quite compatible with most cosmetic oils. Its viscosity breaks down very sharply with an increased amount of a cosmetic oil, and thus it cannot be used as an efficient gelling agent. It may result in oil bleeding or phase split if incorporated in a cosmetic formulation.
In contrast to the art, the rubber-like silicone gel in the present invention comprises a fatty alcohol or aliphatic diol-grafted silicone network, as opposed to a pure silicone network, The compositions of the present invention demonstrate a sufficient compatibility with respect to the targeted cosmetic oils by maximizing the content of the fatty alcohol radical or aliphatic diol radical while preserving the desirable silicone characteristic.
The use of a silicone oil or a cosmetic oil or a mixture thereof, as opposed to a low viscosity silicone oil, also contributes to the beneficial characteristics of the compositions of the present invention.
The use of H.sub.2 PtCl.sub.6.6H.sub.2 O, as opposed to organic metal salts such as tin octoate as a catalyst taught in the art, for the reaction between a fatty alcohol or C.sub.5 -C.sub.22 aliphatic glycol and a methylhydrosiloxane polymer makes the process simpler and more efficient in terms of the yield, purity and cost.